Cheese comes up a lot because many birds are curious about whatever their owner is eating. The honest answer is that cheese is not a natural food for birds, and dairy is something they struggle to digest.
The short answer
Only a tiny amount of hard cheese, and only rarely. Birds are lactose intolerant, so dairy can upset their digestion. Hard cheeses like cheddar are low in lactose, so a crumb now and then usually causes no harm — but cheese is not something a bird needs, and it is easy to overdo.
Why dairy is a problem for birds
Birds do not produce much lactase, the enzyme that breaks down the lactose in milk, so dairy can cause loose droppings and stomach upset. Cheese is also high in fat and salt, none of which suits a small bird. Soft, creamy, processed and flavoured cheeses are best skipped entirely.
Better ways to meet your bird's needs
If you were thinking of cheese for calcium, there are much safer sources: a cuttlebone, a mineral block, and calcium-rich leafy greens like kale and dandelion greens. For protein, a little plain cooked egg is a better occasional choice than cheese. Use our bird food checker to find safe everyday foods.